Decoding the anti-cancer potential of Pexidartinib (PLX3397), a Fms-like tyrosine kinase 3 inhibitor, using next-generation knowledge discovery methods

Acute Myeloid Leukemia (AML) is a complex hematologic malignancy characterized by the rapid proliferation of abnormal myeloid precursor cells. The FMS-like tyrosine kinase 3 (FLT3), a receptor tyrosine kinase, plays a pivotal role in regulating cell survival, proliferation, and differentiation within the hematopoietic system. Mutations in FLT3, particularly internal tandem duplications (ITDs) and point mutations within the tyrosine kinase domain (TKD), are prevalent in AML and are associated with poor prognosis and increased risk of relapse. The development of targeted therapies has revolutionized the landscape of cancer treatment by focusing on the inhibition of kinase signalling. Small-molecule inhibitors designed to selectively target receptor tyrosine kinases, such as PLX3397, have shown promising results in preclinical studies and early phase clinical trials. PLX3397 exerts its inhibitory effects by targeting CSF1R and KIT, leading to the disruption of receptor tyrosine kinase signalling cascades, suppression of leukemic cell growth, and induction of apoptosis. This study emphasizes the significance of FLT3 as a receptor tyrosine kinase as a therapeutic target for PLX3397. After evaluating the usefulness of PLX3397 as an enzyme inhibitor using ADMET prediction, PLX3397 was prepared for molecular docking in the FLT3 crystal structure (PDB: 4XUF). A molecular dynamics simulation was performed on PLX3397 to evaluate its binding affinity and protein stability in a simulated physiological environment. In conclusion, targeting FLT3 as a receptor tyrosine kinase with PLX3397 represents a promising therapeutic strategy for improving outcomes in patients with FLT3-mutated AML. Further clinical investigations are warranted to validate the efficacy and safety of PLX3397 and to optimize treatment strategies for AML patients based on the FLT3 mutational status.


Background:
Acute myeloid leukemia (AML) is a cancer that affects the blood and bone marrow.It involves the rapid growth of abnormal myeloid cells, which are a type of white blood cells responsible for fighting infections.AML accounts for approximately 1% of all cancer cases worldwide [1].Although AML is one of the less common types of cancer compared to other types, its treatment presents several challenges due to the complex nature of the disease and its heterogeneity.Some key challenges in the treatment of AML include high relapse rates, drug resistance, limited treatment options for elderly patients, and the toxicity of intensive chemotherapy [2].AML is characterized by genetic and molecular abnormalities that contribute to its pathogenesis and clinical heterogeneity.Many genes and genetic alterations are commonly associated with AML including FLT3 (FMS-like tyrosine kinase 3).Chromosome 13q12 carries the FLT3 gene, which is commonly referred to as FMS-like tyrosine kinase 3.This gene encodes FLT3, a receptor tyrosine kinase (RTK).The protein encoded by FLT3 is comprised of three domains.The extracellular domain is responsible for ligand binding, the Trans membrane domain anchors the protein to the cell membrane, and the intracellular domain contains tyrosine kinase activity necessary for signal transduction [3].The FLT3 protein is essential for controlling several biological functions, especially hematopoiesis, to generate new blood cells.It contributes to the proliferation and maintenance of hematopoietic progenitor cells (HPCs) and stem cells (HSCs) in the bone marrow.Furthermore, FLT3 signalling pathways control functions such as differentiation, survival, and cell division [4].Mutations in FLT3 have the potential to activate FLT3 signalling, which may promote abnormal cell reproduction and survival.Acute myeloid leukemia (AML) is most commonly associated with two types of FLT3 mutations: point mutations in the tyrosine kinase domain (TKD) and internal tandem duplications associated with the juxta membrane domain.AML patients with these mutations typically have poor prognosis [2], [3], [5].Targeted therapy is a type of cancer treatment that specifically targets molecules or pathways involved in the development and survival of cancerous cells while minimizing damage to normal cells.In contrast to conventional chemotherapy, which frequently targets rapidly dividing cells randomly, targeted therapy intends to interfere with specific molecular targets that are exclusive to cancer cells or are essential for their proliferation and viability.Owing to the significance of FLT3 in the initiation and progression of malignancy, the FLT3 gene is considered an attractive therapeutic target, especially in the treatment of AML patients with FLT3 mutations.FLT3 inhibitors work by targeting the FLT3 receptor tyrosine kinase protein, inhibiting its activity, and thereby slowing the growth and division of leukemia cells.These inhibitors can help reduce AML progression and improve patient outcomes [6].Examples of FLT3 inhibitors include midostaurin, gilteritinib, sorafenib, quizartinib, crenolanib, ponatinib, and FF-10101, which have been approved for the treatment of AML with FLT3 mutations.These targeted therapies are used alone or in combination with standard chemotherapies [2], [3], [6], [7] Pexidartinib (PLX3397) is a novel small chemical molecule that was initially investigated as a potential treatment for tenosynovial giant cell tumor (TGCT), a rare type of tumor, and received FDA approval in 2019 for this indication.It mainly targets two receptor tyrosine kinases (RTKs), colony-stimulating factor 1 receptor (CSF1R) and c-KIT, which are linked to several malignancies and inflammatory disorders [8].By inhibiting these kinases, PLX3397 can block the growth of various cancers [9].Although PLX3397 primarily targets CSF1R and c-KIT, it can also inhibit the expression of other genes.According to the Swiss Target Prediction and SuperPred databases, FLT3 was the top target of this inhibitor.Hence, we document the decoding the anti-cancer potential of Pexidartinib (PLX3397), a Fms-like tyrosine kinase 3 inhibitor, using next-generation knowledge discovery methods.

Target Prediction:
The web servers SuperPred and Swiss Target Prediction are knowledge-based methods that use machine-learning models to predict the targets of the investigated compound.

WebGestalt Analysis:
WebGestalt database was selected for Gene Ontology (GO) terms, including biological process (GO-BP) and molecular function (GO-MF).The reference list for each analysis comprised all mapped gene symbols from the chosen platform genome, Homo sapiens as the species, and the parameters for the enrichment analysis were set at a minimum of 5 and a maximum of 2000 IDs in the category, a false discovery rate (FDR) of P ≤ 0.05, computed using the Benjamini-Hochberg (BH) method, and the significance level of the top 30, as previously described.

Protein Preparation:
The crystal structure of receptor tyrosine kinase FLT3 in complex with the inhibitor quizartinib was obtained from the Protein Data Bank (PDB: 4XUF) and prepared using Schrödinger's Protein Preparation Wizard.Preparation includes the addition of missing hydrogen atoms to residues, correction of metal ionization states, and removal of water molecules > 5 Å from protein residues.Using Epik, the protonation state of the residues was generated and the formal charge on the metal ions was adjusted.After removing the extra protein subunit of the multi-subunit protein and additional ligands, protein processing was refined by predicting the pKa of the ionizable residues using PROPKA.Finally, the restrained minimization of the protein was performed using the OPLS4 force field.

Ligand Preparation:
PLX3397 and co-crystallized ligands were prepared for docking using Schrödinger's LigPrep tool.This tool converted the 2D structures to 3D structures and energy-minimized those using the OPLS3 force field.After adding hydrogens, all possible ionization states and tautomeric forms were created at a pH range of 7.0 _ 2.0 by Epik; the desalting option was also chosen.The hydrogen bonds were optimized by predicting the pKa of the ionizable groups using PROPKA.

Grid Generation and Molecular Docking:
The co-crystallized structure of AC220 was used as the reference to define the grid box.Glide's Receptor Grid Generation tool was used to determine the binding pocket.The grid box dimensions were set to 10 Å in each of the X, Y, and Z directions using the default settings without any modifications.Docking was then performed using the Schrödinger suite "Ligand Docking" tool.The selected docking protocol was extra precision (XP), and the ligand sampling method was flexible.All other settings were the default.

Molecular dynamics (MD) simulation:
MD simulations were performed using Desmond software in the Schrödinger suite, limiting the run to include only the isomers with the highest docking scores.To ensure accurate results, the protein-ligand complex was immersed in a solvated system created by placing the complex in an orthorhombic water box that extended 10 Å beyond the atoms in the complex.Na + and Cl -counterions were added to neutralize the system.The simulation was set to continue for 100 ns, maintaining a constant temperature of 300 K and pressure of 1.01325 bars.

Results and Discussion:
Drug Targets: PLX3397 targets several classes of proteins based on the data obtained from Swiss Target Prediction and Superpred (Tables 1  and 2).SwissTargetPrediction for the ligand molecule PLX3397 has shown probable attachment to the biological system.The prediction report revealed the top probable targets given in the pie chart.The pie-chart shows that 31% of the total targets among the feasible targets are kinases, followed by family A G protein-coupled receptors (13%) and proteases (12%) (Figure 1).PLX3379 interferes with many biological processes including regulation, response to stimulation, and metabolism.It targets many cellular components, particularly the membrane, the endomembrane system, and protein-containing complexes.Furthermore, many molecular functions, including protein binding, ion binding, and transfer activities, are affected by PLX3397 (Figure 2).

Gene Ontology biological process:
PLX3397 may interfere with many biological processes, such as protein autophosphorylation, ERK1 and ERK2 cascades, and inositol lipid-mediated signaling (Figure 3).
The ERK1/2 (Extracellular Signal-Regulated Kinase 1/2) cascade, also known as the MAPK/ERK pathway, plays a critical role in signaling cascades, and transmits extracellular signals to intracellular targets.This pathway controls signaling involved in various cellular processes, including cell proliferation, differentiation, survival, and migration in both healthy and pathological cases [10].The activation of ERK1/2 has an important role in the development and progression of cancer.In cancer cells, mutations or alterations in upstream signaling molecules such as receptor tyrosine kinases (RTKs), Ras proteins, or Raf kinases can lead to constitutive activation of the ERK1/2 pathway.This prolonged activation of ERK1/2 promotes uncontrolled cell growth and survival, which are hallmark features of cancer [10], [11] Moreover, ERK1/2 signaling can crosstalk with other signaling pathways implicated in cancer, thereby amplifying oncogenic signaling networks.For example, ERK1/2 interacts with the PI3K-Akt pathway leading to increased cell proliferation and survival.Additionally, ERK1/2 signaling can influence the expression of genes involved in epithelial-mesenchymal transition (EMT), a process associated with cancer metastasis [12], [13].As ERK1/2 signaling plays a central role in cancer, targeting this pathway has been the focus of cancer therapy.Small-molecule inhibitors targeting key components of the ERK1/2 pathway, such as Raf and MAPK/ERK kinase (MEK), have been developed and are being evaluated in clinical trials for various cancer types.Because PLX3397 targets upstream regulators of ERK1/2 signaling, such as c-Kit and CSF1R, it may also have therapeutic potential in certain cancers by indirectly modulating ERK1/2 activity.Based on the WebGestalt database, among the 389 genes related to the ERK1 and ERK2 cascades, only 16 genes were related to PLX3397.FLT3 is one of the genes related to the ERK signaling pathway, and PLX3397, which targets FLT3, may indirectly inhibit the ERK1/2 signaling pathway, which plays a key role in cancer development and progression (Table 3).

Gene Ontology Molecular Function:
PLX3397 targets various molecules and pathways involved in cancer development and progression.Transmembrane receptor protein kinase and phosphatidylinositol 3-kinase activities are examples of molecular processes that PLX3397 might influence (Figure 4).Transmembrane receptor protein kinase activity refers to the ability of receptor tyrosine kinase proteins (RTKs) to transfer signals across the cell membrane from outside to inside.These proteins typically consist of both extracellular and intracellular domains.The phosphorylation of intracellular domains triggers a series of downstream signaling events within the cell that regulate processes such as cell growth, differentiation, and survival, which are essential for various physiological processes.
Approximately 99 genes control transmembrane receptor protein kinase activity, and only 15 genes could be targeted by PLX3397, and FLT3 is one of these genes (Table 4).FLT3 encodes Fms-like tyrosine kinase 3 (FLT3), a transmembrane receptor protein kinase primarily expressed on the surface of hematopoietic stem and progenitor cells in the bone marrow and is involved in cell survival, proliferation, and differentiation.Mutations in FLT3, such as internal tandem duplications (ITDs) and point mutations in the tyrosine kinase domain, are frequently found in acute myeloid leukemia (AML).These mutations lead to constitutive activation of FLT3 signaling, promoting uncontrolled growth and survival of leukemia cells .Phosphatidylinositol 3-kinase activity is regulated by 99 genes, of which only seven can be targeted by PLX3397.FLT3 is one of the genes that control phosphatidylinositol 3-kinase activity (Table 5).FLT3 is frequently mutated and dysregulated in acute myeloid leukemia (AML), particularly through internal tandem duplication (ITD) mutations.FLT3-ITD mutations stimulate FLT3 kinase activity, which in turn activates downstream signaling pathways.Dysregulated signaling promotes cell proliferation, survival, resistance to apoptosis, contributing to the pathogenesis and progression of AML.Targeting FLT3 by PLX3397 could interfere with phosphatidylinositol 3-kinase activity, which ultimately interferes with the development of malignancy.
To validate the efficacy of PLX3397 as an inhibitor of FLT3, computational studies, including docking, molecular dynamics simulation, and ADMET prediction, were performed.These experiments assessed binding affinity and identified key interactions between PLX3397 and FLT3.A crystallized structure of the FLT3 protein with a co-crystalized ligand, quizartinib (AC220), was obtained from the Protein Data Bank (PDB: 4XUF).Quizartinib (AC220) is an inhibitor that binds to the ATPbinding pocket of the FLT3 kinase domain in both wild type and mutated FLT3 [16].

Ligand and protein preparation and molecular docking:
PLX3397 and a co-crystallized ligand (AC220) were prepared for docking, where energy-minimized 3D structures were generated and all possible ionization and tautomeric states were created.Both PLX3397 and the co-crystallized ligand (AC220) showed two isomers after they were converted into 3D structures.For docking, the FLT3 crystal structure (PDB ID: 4XUF) was selected because of the similarity between the structure of PLX3397 and the co-crystallized ligand (AC220) (Figure 5).The PDB file of the 4XUF crystal structure was downloaded from the Protein Data Bank (PDB), which was then prepared and minimized using Schrödinger's Protein Preparation Wizard.The docking process started with the definition of the grid box around the co-crystallized ligand to determine the docking location using the receptor-grid-generation tool in Maestro Schrödinger.To validate the accuracy of the docking method, redocking of the co-crystallized ligand AC220 was performed back into the prepared protein.The primary goal of re-docking was to evaluate the accuracy of the predicted binding pose by comparing it to the crystallographic pose of AC220.The crystallographic pose and predicted binding pose were similar, with a root mean square deviation (RMSD) value of 1.4568.This finding indicates agreement between the predicted and observed binding interactions of AC220 (Figure 6).After docking validation, docking of the 3D structures of AC220 and PLX3397 was performed using the extra precision (XP) mode.Docking produced derivatives that were ranked based on their score and approximated the free energy of binding; the more negative the value, the stronger the binding.The ranking depends on different docking scores, including gscore (best for ranking different compounds), emodel (best for ranking conformers), and XP gscore.Table 6 displays the docking scores of AC220 and its isomer, and PLX3397 and its isomer.Based on the glide gscores that sort docked compounds according to poses, the first PLX3397 isomer showed a better gscore (-15.313kcal/mol) than the first isomer of the native reference AC220 (-9.830 kcal/mol).Because of the docking scores of these two isomers, they were used for further computational studies.The 3D docking representation revealed that both PLX3397 and AC220 H-bonded with Cys-694 and Glu-661.Phe-830 residue interacts with the aniline of AC220 via π-π stacking and with the middle pyridine of PLX3397 via π-cation stacking.Furthermore, the middle pyridine of PLX3397 forms another π-cation stacking with Phe-691, which explains its high docking score compared to that of AC220.The H-bonding of aniline in AC220 with the backbone carboxyl of Asp-829 corresponds to the H-bonding of the nitrogen of pyrrol in PLX3397 with the side chain carboxyl of Glu-692 (Figure A7 and A8).The 2D depictions of the binding modes of PLX3397 and AC220 were similar to those of the 3D depictions, with some differences.Glu-661, Glu-692, and Cys-694 form H-bonds with both PLX3397 and AC220.Phe-691 interacted through π-π stacking with the aniline of AC220 and with the middle pyridine of PLX3397.Phe-830 form pi-pi stacking with aniline ring while Asp-829 and Glu-661 interact with (tert-butyl) isoxazol)-phenylurea by hydrogen bonds (Figure B7&B8).The molecular surface displayed in Figure B9 shows that PLX3397 occupied the binding pocket of the crystal structure.The co-crystallized ligand (AC220) seemed to have similar interactions with the protein; however, morpholine at the end of the chain did not occupy the distant pocket and remained exposed to the solvent (Figure A9).

Molecular dynamic simulation:
MD simulation is a powerful computational technique used to study the movement and interactions of ligands and proteins over time.It is useful to understand the dynamics of proteinligand complex stability under various conditions, such as changes in temperature, pressure, or chemical environment.Desmond software was used to perform MD studies on PLX3397 and native ligand (AC220) isomers with the best docking scores.
(MD) simulation study, where complex structures were optimized under specific pH conditions (ranging from 7.0 to 2.0) followed by a simulation period of 100 nanoseconds (ns) to observe the behavior and convergence of system properties.The MD simulation was run in which protein-ligand complex structures were optimized under specific pH conditions (ranging from 7.0 to 2.0), followed by a simulation period of 100 ns to observe the behavior and convergence of the system properties.
Analyzing interaction maps and root mean square deviation (RMSD) plots provides valuable insights into the stability and dynamics of these protein-ligand complexes.The stability of the complexes during a 100 ns simulation with reference to the initial time point (0 ns) was estimated by plotting the Root Mean Square Deviation (RMSD) of the protein-ligand complex over time.RMSD values of FLT3 protein plotted on the left y-axis and ligands plotted on the right y-axis.PLX3397 and AC220 complexes exhibited minor fluctuations within an acceptable range of 1-3 Å, indicating their stability.However, the AC220 complex showed more fluctuations than the PLX3397 complex, which reflects the stability of PLX3397 in the binding pocket (Figure 10).
The molecular interactions between the binding pocket amino acid residues and ligands that persisted for at least 30.0% of the simulation time within the selected frame (0.00 to 100.00 ns), as well as the docked poses that remained stable throughout the 100 ns simulation time, are displayed in Figure 11B.As shown in the top part of Figure 11B, Glu-661 formed direct H-bonds as well as water bridges with AC220 and had a normalized value of ~1.9, which indicates that the interactions were maintained for ~190% of the simulation time.A value >1 indicates a combination of more than one type of binding interaction.Other important interactions were Phe-691, Glu-692, Cys-694, Asp-829, and Phe-830, with values of approximately 1.0, 0.8, 0.8, 1.1, and 0.9, respectively.The bottom part of Figure 11B shows the key interactions of PLX3397 with Phe-691, Glu-692, Cys-694, Lue-818, and Asp-829, with values of ~0.9, ~1.0, ~1.0, ~0.7, and ~0.9, respectively.Figure 11A shows only the protein-ligand interactions that equal or exceed 30% of the simulation period.The top part of Figure 11A shows that Glu-661 interacts with AC220 via three binding types, including two H-bonds with di(azaneyl)methanone that existed for 99% and 52% of the simulation time and a water bridge 30%.Asp-829 H-bonded with the carbonyl of di(azaneyl)methanone continued for 94%, and Phe-691 formed pi-pi stacking with aniline held at 68%.Both Glu-692 and Cys-694 formed a water bridge with imidazo benzothiazole during 85% and 56% of the simulation period, respectively.The bottom part of Figure 11A shows that the residues interacted with PLX3397 for more than 30% of the simulation time.Cys-694 and Glu-692 H-bonded to terminal pyrrolopyridine were maintained at 99% and 100%, respectively.Phe-691 pi-pi staked and Asp-829 H-bonded with the middle pyridine for 81 and 78% of simulation time respectively.
In Silico ADMET Properties of PLX3397: With Maestro's QikProp Schrödinger's module, the druglikeness and ADMET characteristics of the PLX3397 isomer were predicted in terms of absorption, distribution, metabolism, excretion, and toxicity.The module can predict a wide range of physicochemical properties and other descriptors, including the number of reactive functional groups and possible metabolites, quickly and accurately.This allows the detection of compounds that may represent challenges in the later stages of drug discovery and development.
Therefore, unnecessary experiments that will ultimately fail in clinical trials can be excluded.ADMET prediction evaluates the usefulness of PLX3397 isomers by identifying and assessing their druglikeness, physicochemical properties, and anticipated toxicity profiles.For the PLX3397 isomers, several descriptors were predicted, and the majority of the ADMET descriptor predictions were within the recommended range or close to it.Table 7 presents the expected ADMET properties and descriptors.

Conclusion:
FLT3 (Fms-like tyrosine kinase 3) is a protein that plays a role in cell growth and division.Mutations in FLT3 are commonly found in acute myeloid leukemia (AML), a type of cancer that affects the blood and bone marrow.PLX3397 is a small-molecule inhibitor that targets receptor tyrosine kinases, including CSF1R and KIT.It is being studied for its potential in the treatment of certain cancers, particularly that involving macrophage infiltration.In this study, in silico experiments, including molecular docking, molecular dynamics simulations, and ADMET prediction, were performed to determine the binding interaction of PLX3397 with FLT3.These studies intersect in cancer research, particularly in understanding the molecular mechanisms underlying AML, developing targeted therapies derived from PLX3398 against specific molecular targets, such as FLT3 mutations, and utilizing computational approaches (in silico) to accelerate drug discovery and optimize treatment strategies.

Figure 1 :
Figure 1: Pie chart of target classes based on the SwissTargetPrediction tool.

Figure 2 :Figure 3 :
Figure 2: Gene ontology (GO) Slim Summary of the differentially expressed genes (DEGs) used in WebGestalt analysis for biological processes (red), cellular components (blue), and molecular functions (green)

Figure 4 :
Figure 4: The bar shows the results of the analysis for molecular function affected with PLX3397 [14].Phosphatidylinositol 3-kinase (PI3K) activity is a critical component of the intracellular signaling pathways involved in regulating various cellular processes, including cell growth, survival, proliferation, metabolism, and motility.PI3K catalyzes the phosphorylation of phosphatidylinositol (PI) lipids to generate phosphatidylinositol 3,4,5-trisphosphate (PIP3).PIP3 activates downstream signaling proteins, which, in turn, regulate multiple cellular functions.Abnormal activation of PI3K signaling promotes uncontrolled growth and progression of cancer.Therefore, targeting PI3K activity has emerged as a

Figure 5 :
Figure 5: Chemical structures of native inhibitors (AC220) and PLX3397.AC220 (1-(5-(tert-butyl)isoxazol-3-yl)-3-(4-(6-(2 morpholino ethoxy) benzo[d]imidazo [2,1-b]thiazol-2-yl) phenyl)urea ), consisting of aliphatic morpholinoethoxy bound to imidazobenzo-thiazole connected to tert-butyl-isoxazolphenylurea.PLX3397 5-((5-chloro-1H-pyrrolo[2,3-b]pyridin-3yl)methyl)-N-((6-(trifluoromethyl)pyridin-3-yl)methyl)pyridin-2amine made of chloro-pyrrolopyridin bound to methylpyridinamine that bound to trifluoromethylpyridin.Based on their structures, both AC220 and PLX3397 were expected to have similar 3D conformations in the binding pocket of the protein.The PDB file of the 4XUF crystal structure was downloaded from the Protein Data Bank (PDB), which was then prepared and minimized using Schrödinger's Protein Preparation Wizard.The docking process started with the definition of the grid box around the co-crystallized ligand to determine the docking location using the receptor-grid-generation tool in Maestro Schrödinger.To validate the accuracy of the docking method, redocking of the co-crystallized ligand AC220 was performed back into the prepared protein.The primary goal of re-docking was to evaluate the accuracy of the predicted binding pose by comparing it to the crystallographic pose of AC220.The crystallographic pose and predicted binding pose were similar, with a root mean square deviation (RMSD) value of 1.4568.This finding indicates agreement between the predicted and observed binding interactions of AC220 (Figure6).

Figure 7 :
Figure 7: Binding mode of the co-crystallized ligand AC220 in the active site of FLT3 (PDB ID: 4XUF).AC220 is shown as a greenstick, whereas hydrogen bonds and ionic bonds are represented by yellow and blue dotted lines, respectively.(A)3D representation of FLT3 complexed with AC220 and (B)2D depiction.

Figure 8 :Figure 9 :
Figure 8: Binding mode of PLX3397 to the active site of FLT3 (PDB ID: 4XUF).PLX3397 is shown as green sticks, while hydrogen bonds and ionic bonds are represented by yellow and blue dotted lines, respectively.(A) 3D representation of FLT3 complexed with PLX3397 and (B) 2D depiction

Figure 11 :
Figure 11: (A) Schematic diagram showing the detailed 2D atomic interactions of the reference ligands AC220 and PLX3397 with FLT3 that occurred over 30% of the simulation time in the selected trajectory.(B) Stacked-bar graph of FLT3 interactions with AC220 and PLX3397 throughout the simulation period.

Table 7 : In silico ADMET Predicted properties of PLX3397 isomers.
[17]mmended range: 95% of known drugs; #Stars: number of descriptors that fall outside the 95% range of the same values for known drugs.Large star numbers indicate less drug-likeness, and vice versa; dipole: computed dipole moment; SASA: Total solvent accessible surface area; DonorHB: estimated number H+ to be donated in HB; AcceptHB: estimated number H+ to be accepted in HB; QLogPo/w: predicted octanol/water partition coefficient; QPlogS: Predicted aqueous solubility; QPlogKhsa: Prediction of binding to human serum albumin; #Metab: number of possible metabolic reactions; QPlogBB: Predicted brain/blood partition coefficient; % Human Oral Absorption: Predicted human oral absorption on a 0 to 100% scale; QPlogHERG: Predicted IC50 value for blockage of HERG K+ channels; CNS: Predicted central nervous system activity; #RtvFG: Number of reactive functional groups.This computational study supports the predictions obtained from SwissTargetPrediction and SuperPred for the antitumor activity of PLX3397 through its interaction with FLT3.As FLT3 plays a critical role in AML pathogenesis, targeting FLT3 signalling represents a promising therapeutic strategy for the development of novel drugs.PLX3397 can be an indirect FLT3 inhibitor, and there has been some research interest in its potential application in acute myeloid leukemia (AML) because of its ability to target the tumor microenvironment by inhibiting CSF1R, which is involved in the regulation of macrophages and other immune cells within the bone marrow[17].While PLX3397 primarily targets (CSF1R) and c-kit, it has been observed to have inhibitory effects on FLT3 signalling, particularly in cells with FLT3-ITD mutations [9]. *